Research On Heat Transfer Mechanism And Energy Saving Of Micro Channel Heat Pipe Implanted In Wall System Under Hot And Humid Climate

With the continuous development of society,the way of life has undergone great changes.The function of building has transformed from a simple shelter for wind and rain to a complex that provides comfortable living space and integrates functions such as consumption,and entertainment.As a result,the proportion of building energy consumption in the total social energy consumption continues to soar.Recently,Energy-saving and environment-friendly economy are advocated all over the world.Among them,the issue of building energy consumption has attracted much attention,and energy-saving measures have emerged in an endless stream in terms of building structural materials,use functions,and operation cycles.In this thesis,based on the structural characteristics of the wall in the building envelope,a flat plate evaporating end loop heat pipe is designed to be embedded in the wall,and a new passive adaptive building envelope is proposed combining the characteristics of the heat pipe and the wall.The evaporating end and the condensing end of the heat pipe are of micro-channel plate structure,which can closely fitted with the inner and outer surfaces of the traditional wall structure,and are connected by the air pipe and the liquid pipe across the wall,so as to enable the circulation of the internal working fluid across the wall for efficient heat transfer.In this thesis,theoretical analysis,heat transfer experiment and simulation research are carried out,and the heat transfer performance of the system under different conditions and the effect on the indoor environment are obtained.Firstly,extensive literature survey has carried out on the energy-saving technologies for building walls and the research on the combination of heat pipes and building walls.The advantages and disadvantages of different energy-saving technologies are compared and analyzed,and the advantages of heat pipe combined into wall technology are discussed.In addition,extensive investigations has carried out on the research of different heat pipe structures,the advantages and disadvantages of various heat pipe structures and the matching degree between different structures and the wall were compared and analyzed.Finally,the structure of the heat pipe is determined as a loop heat pipe,in which the evaporating end and the condensing end are micro-channel plates.Secondly,the theoretical analysis of the designed heat pipe structure is carried out,and the heat transfer limit,heat transfer resistance and other performance parameters of the heat pipe are calculated.Subsequently,the heat pipe components were fabricated and the pre-experiment of heat transfer was carried out to confirm that the temperature distribution of the heat pipe under the actual heat transfer was consistent with the theoretical analysis,so that the heat pipe could be implanted into the wall.Based on the energy conservation,heat balance equation and the characteristics of the heat pipe embedded in the wall system,the theoretical analysis of the heat transfer process of the system is carried out,and the theoretical heat transfer performance and laws of the system are obtained.One-dimensional steady-state heat transfer experiments and heat transfer experiments under different seasonal environment simulations were carried out.Results show that in the one-dimensional steady state experiment,the thermal resistance of the system fluctuates around the theoretical value（0.165K/W）after the heat transfer process is stabilized,and the amplitude less than 10%.In the environmental simulation heat transfer experiment,the dynamic heat transfer thermal resistance of the system is always kept near the theoretical value,and the average thermal resistance is about 0.184K/W,which deviates from the theoretical value by about 11.5%.Experiments show that the heat transfer thermal resistance of the heat pipe embedded in the wall system is much smaller than the thermal resistance of the traditional wall（10.962K/W）.Finally,a three-dimensional room model is established,and the effect of the heat pipe embedded in the wall system in the actual indoor space is simulated and analyzed.The results show that when the system is installed on the south wall of the building,and the area accounts for 22.2% of the total building wall,compared with the use of traditional wall structure,the indoor temperature rises by up to 2.88°C during the daytime in winter,and decreases by up to 1.51°C at night in summer.In addition,the control scheme of system is proposed to avoid the environmental deterioration caused by the passive and efficient heat transfer of the system at night in winter and daytime in summer,thus the system can start efficient heat transfer process or maintain the traditional wall insulation performance according to different needs.